The present invention relates to a dropping container and, more specifically, to a dropping container for containing an unstable substance which reacts, decomposes or fumes when it contacts air and for dropping the substance upon use.
Japanese Patent Publication No. 42-12318 (12,318/1967) discloses that an acrylic resin adhesive comprising alkylboron as a curing agent shows strong adhesion to a bone and a tooth and is useful for dental and surgical applications.
However, the alkylboron used as a curing agent is an unstable substance which readily reacts with oxygen in the air and loses its activity thereby. A curing agent which overcomes this defect is disclosed by Japanese Patent Publication No. 51-37092 (37,092/1976).
That is, Japanese Patent Publication No. 51-37092 discloses an adhesive filler for dental and surgical applications which comprises a product obtained by reacting trialkylboron with 0.3 to 0.9 mol of oxygen as a curing agent.
The product as a curing agent is used to suppress the adhesion of trialkylboron to the least possible degree so as to remove the ignitability of the trialkylboron. However, this product is also an unstable substance, though not so unstable as trialkylboron.
Hitherto, such an unstable substance has been preserved in a closed ampul, and the ampul has been broken on use and sealed up again after use. However, it takes much time and labor to break and seal up the ampul. In addition, since the unstable substance in the ampul contacts air even for a short period of time from the breakdown to the sealing of the ampul, it has often reacted with air to lose its activity.
To overcome the above defect, Japanese Laid-open Utility Model Application No. 50-139498 (139498/1975) discloses a dropping container in which a closing portion having a thin tube for dropping is provided at one end of a cylindrical body made from a metal or glass and a movable plug made from fluororubber or fluororesin is provided near the other end, and the movable plug is pushed by rotating a screw attached to the cylindrical body or a container for mounting the cylindrical body to take out a predetermined amount of a curing agent filled in the cylindrical body.
This container enables a required amount of alkylboron to be taken out by dropping. However, since a curing agent present in the thin tube for dropping contacts the outside air through an opening at the tip of the thin tube, it is almost impossible to prevent the curing agent from deteriorating gradually even with the tip capped when it is preserved for a long time.
Further, Japanese Laid-open Utility Model Application No. 5-65900 (65,900/1993) discloses a dropping container having such a structure that entry of air from the outside can be inhibited almost perfectly to prevent the deterioration of a curing agent when it is preserved for a long time.
However, since this dropping container has such a structure that it is sealed up by an elastic body itself to preserve a chemical, the elastic body may deteriorate due to the chemical through its long-time use.